Mechanical Design and Workspace Optimization of a Flexible Parallel Manipulator for Minimally Invasive Surgery

Minimally invasive surgery (MIS) provides adequate benefits such as less trauma, higher safety and shorter recovery cycle. However, the limited dexterity in small size and low load capacity of current surgical robots prevents its development. This paper proposes a flexible surgical manipulator with a two-stage 3-PRS mechanism. The mechanical design of the manipulator is described in detail and the kinematic model is established. The analytical expression of the inverse kinematics solution of the proposed mechanism is derived by solving the motion equation. Based on the inverse kinematics solution, the reachable workspace of the manipulator is achieved, considering the geometric constraints. The influence of main parameters of the proposed manipulator on its reachable workspace is explained via parameter analysis. Results show that these parameters of the radius of the platforms and the length of the connecting links are related to the reachable workspace of the manipulator. Furthermore, a mechanism prototype is presented and the working principle of the parallel mechanism is verified.